Conext XW+ 8.5kW when they get hot

Marc KurthMarc Kurth Solar Expert Posts: 899 ✭✭✭✭
Hey, Dave:
I need a sanity check. I am working on a project with a pair of Conext XW+  8.5kW inverters in parallel.
The load is 12kw continuous for several hours. Looks like these are rated 6.8 kw continuous at 25 C. I saw the 6KW at 104F which puts me right on the line - at 100% of rating.
Would you be comfortable running the pair at close to 100% load if the ambient climbed a bit? I cannot define "a but" just yet, but I am uncomfortable with their thermal load calc's.
Any experience with these units when the ambient sneaks up?
Marc
I always have more questions than answers. That's the nature of life.

Comments

  • Dave AngeliniDave Angelini Solar Expert Posts: 6,076 ✭✭✭✭✭
    XW is probably the best designed electronics out there for heat and pushing the limits. XW will take care of itself and tell you what it is doing to stay safe at high ambient. For a master slave combo 12Kw @ 100F for several hours, you might have to supplement the cooling with an external fan. Make sure there is plenty of space above XW and on it's sides. Make sure the fan filters are maintained.

    I am assuming the xw+ 8.5KW is not for NA as XW NA is 6.8KW split phase.

    What are you running?
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • Marc KurthMarc Kurth Solar Expert Posts: 899 ✭✭✭✭
    edited December 2019 #3
    Thanks, Dave - that is exactly the kind of confirmation (or denial) that I was seeking and I appreciate it very much! I'm just on the battery side of the project, but I want to keep the customer out of trouble.
    Yes, Sir. This is for an overseas, very remote communications and data center with a skeleton crew onsite. They already have redundant gasoline and diesel generators, but they also seem to have money to burn - so battery backup is being added. I tried hard to push them toward large flooded cells, but they are insisting on multiple strings of 2v AGM cells to allow continued operation on partial failure, and no maintenance. I am approving my side of this layout because, by design, the bank will sit on float for very long periods.
    I have done many offgrid residences with two strings of 2v, 1250 ah cells, plus farms and ranches with three and four strings - but only one other with 6 or more strings. I still maintain that the project should use fewer large flooded cells and they have that in writing - but that is not my decision. I would like to be the guy getting the order for the copper bus bars!
    Marc
    I always have more questions than answers. That's the nature of life.
  • mcgivormcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    edited December 2019 #4
    @Marc Kurth
    There is one observation which may or may not be relevant, the general construction of the inverter should be sound, able to power the loads as required without issues but from my experience with the SW line, the fans are prone to failure. Since the fans are outsourced they are not necessarily a design fault but rather an Achilles heel if used in tropical climates where they are constantly running. Both my fans failed for the same reason  within a year running 24/7, they were replaced with cheap alternative fans which have proven to be far more reliable.

    Should this be a concern I will gladly post a picture of the fans in question, obviously if the fans are not called for on a regular basis they may be fine for intermittent use. The fans may or may not have been substituted with others, but if your reputation is on the line and used in harsh environmental conditions you may take this into consideration.


    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • Marc KurthMarc Kurth Solar Expert Posts: 899 ✭✭✭✭
    I appreciate the input!
    Marc
    I always have more questions than answers. That's the nature of life.
  • Dave AngeliniDave Angelini Solar Expert Posts: 6,076 ✭✭✭✭✭
    CSW and XW cooling are completely different BTW. (just about everything in CSW is less robust)  XW is designed to run convection cooled with dead fans for a long time. It also has filters if there is someone in charge to maintain. XW fans are a better grade also. 
    XW was built for this kind of thing. CSW was built to sell for a low price.

    If you feel that your reputation is on the line, you should insist 3 XW's. They can share the loads better and live longer.
     That is what I would do if I even thought I would come up against the limits for offgrid. Especially if someone else is paying for it. ;)


    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • Marc KurthMarc Kurth Solar Expert Posts: 899 ✭✭✭✭
    edited December 2019 #7
    Thanks, Dave. The equipment selection was by their engineer, but I was asked for an opinion. I did already recommend that they go to four inverters. The cost of additional inverters and associated installation is not extreme when looking at the overall project cost. They are paying big bucks for double/triple redundancy, but they designed in an obvious failure point with only two inverters. Yes, they can shed some loads in an emergency, but that is not what the design criteria is.
    The temperature control problem still bothers me, because mechanical cooling is really, really expensive via battery. My "back of an envelope" calcs say that the entire structure will get way hotter than they think. If something doesn't change soon, I may back out of the project.
    A smart man knows when to fire a customer.
    I always have more questions than answers. That's the nature of life.
  • Dave AngeliniDave Angelini Solar Expert Posts: 6,076 ✭✭✭✭✭
    With 3 or 4 inverters cooling will not be an issue. These were built to do this. You just need to make sure the structure is being vented and not going to oven mode.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

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